Important Notice:For safety reasons, while braking, only the sensors sense obstacles, the LCD monitor will be active.Try to keep the sensors at the same level.In order to avoid detecting the ground, please keep the sensor and the ground has a distance of 19.6~23.6 in (21.6 in suggested).Please always keep the arrow (back of each sensor) up while installing.The Control Box should be mounted on side of the car trunk.